Electrostatic stability and encapsidation of charged nano-droplets

Javidpour, Leili; Božič, Anže; Naji, Ali; Podgornik, Rudolf

doi:10.1039/c3sm52139g

Cited by 6 publications

(21 citation statements)

References 56 publications

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“…The dressed multivalent-ion theory has been tested extensively against implicit-and explicit-ion simulations [69,[87][88][89][90][91] and turns out to have a wide range of validity in the parameter space when the surfaces bear uniform charge distributions. Similar simulations are still missing in the case of randomly charged surfaces with multivalent ions mostly because of a significantly large increase in the computational time, which would be required in oder to produce reliable quenched disorder averages.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging and charge inversion

Naji

Ghodrat

Komaie-Moghaddam

et al. 2014

The Journal of Chemical Physics

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We study the distribution of multivalent counterions next to a dielectric slab, bearing a quenched, random distribution of charges on one of its solution interfaces, with a given mean and variance, both in the absence and in the presence of a bathing monovalent salt solution. We use the previously derived approach based on the dressed multivalent-ion theory that combines aspects of the strong and weak coupling of multivalent and monovalent ions in a single framework. The presence of quenched charge disorder on the charged surface of the dielectric slab is shown to substantially increase the density of multivalent counterions in its vicinity. In the counterion-only model (with no monovalent salt ions), the surface disorder generates an additional logarithmic attraction potential and thus an algebraically singular counterion density profile at the surface. This behavior persists also in the presence of a monovalent salt bath and results in significant violation of the contact-value theorem, reflecting the anti-fragility effects of the disorder that drive the system towards a more "ordered" state. In the presence of an interfacial dielectric discontinuity, depleting the counterion layer at the surface, the charge disorder still generates a much enhanced counterion density further away from the surface. Likewise, the charge inversion and/or overcharging of the surface occur more strongly and at smaller bulk concentrations of multivalent counterions when the surface carries quenched charge disorder. Overall, the presence of quenched surface charge disorder leads to sizable effects in the distribution of multivalent counterions in a wide range of realistic parameters and typically within a distance of a few nanometers from the charged surface.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging and charge inversion

Naji

Ghodrat

Komaie-Moghaddam

et al. 2014

The Journal of Chemical Physics

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“…In the more general context of dressed multivalent-ion theory, the leading-order virial terms can generate both the SC and WC behaviors of the system in the limits of small and large screening parameters, respectively [34]. The predictions of this theory were analyzed for uniformly charged surfaces (and also for strictly neutral surfaces) and were compared with extensive numerical simulations elsewhere [7,[34][35][36][37][38].…”

Section: B General Form Of the Interaction Free Energymentioning

confidence: 99%

“…In these situations, one deals with a difficult problem in which neither the WC nor the SC limiting laws can be applied without reservations. For such asymmetric Coulomb fluids, a generalized dressed multivalent-ion approach, that bridges the two limits in one single theoretical framework, has been introduced [7,34] and tested against extensive explicit-and implicition simulations [7,[34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

“…Neither the WC nor the SC paradigm can be consistently applied to this situation where the system is electrostatically part strongly and part weakly coupled. In this case dressed multivalent-ion theory, based on piecewise application of the WC and SC formalism, has been shown to posses a robust regime of validity [7,[34][35][36][37][38]. Other cases demanding an extension and/or modification of the WC-SC framework have been recently reviewed in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions

et al. 2015

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We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to the (equal) mean charges on the two surfaces and the osmotic pressure of monovalent ions residing between them. These effects can be quite significant even with a small degree of surface charge disorder relative to the mean surface charge. The strong coupling, disorder-induced attraction is typically much stronger than the van der Waals interaction between the surfaces, especially within a range of several nanometers for the inter-surface separation, where such effects are predicted to be most pronounced.

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“…[7, 81, 99-104, 106-108, 112-119] and references therein), or more generally, the dressed multivalent-ion theory [27,103,120,121], which provides a very good approximation for the study of asymmetric Coulomb fluids over a wide range of parameters as verified by explicit-ion and implicit-ion simulations. The dressed multivalent-ion theory reproduces the mean-field Debye-Hückel theory and the standard strong-coupling theory for counterion-only systems [99-103, 106-108, 112-118] as two limiting theories in the regime of large and small Debye screening lengths and, therefore, bridges the gap between these two limits [27,103,[120][121][122][123]. The key step in this latter approach is to integrate out the degrees of freedom associated with monovalent ions by means of a linearization approximation, justified only for highly asymmetric Coulomb fluids q ≫ 1, and yielding an effective Debye-Hückel (DH) interaction between the remaining multivalent ions and the surface charges (if any) [120].…”

Section: A Formal Backgroundmentioning

confidence: 78%

Ion-mediated interactions between net-neutral slabs: Weak and strong disorder effects

Ghodrat

Naji

Komaie-Moghaddam

et al. 2015

The Journal of Chemical Physics

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We investigate the effective interaction between two randomly charged but otherwise net-neutral, planar dielectric slabs immersed in an asymmetric Coulomb fluid containing a mixture of mobile monovalent and multivalent ions. The presence of charge disorder on the apposed bounding surfaces of the slabs leads to substantial qualitative changes in the way they interact, as compared with the standard picture provided by the van der Waals and image-induced, ion-depletion interactions. While, the latter predict purely attractive interactions between strictly neutral slabs, we show that the combined effects from surface charge disorder, image depletion, Debye (or salt) screening, and also, in particular, their coupling with multivalent ions, give rise to a more diverse behavior for the effective interaction between net-neutral slabs at nano-scale separations. Disorder effects show large variation depending on the properly quantified strength of disorder, leading either to non-monotonic effective interaction with both repulsive and attractive branches when the surface charges are weakly disordered (small disorder variance) or to a dominating attractive interaction that is larger both in its range and magnitude than what is predicted from the van der Waals and image-induced, ion-depletion interactions, when the surfaces are strongly disordered (large disorder variance).

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Electrostatic stability and encapsidation of charged nano-droplets

Cited by 6 publications

References 56 publications

Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging and charge inversion

Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging and charge inversion

Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions

Ion-mediated interactions between net-neutral slabs: Weak and strong disorder effects

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